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Growth of Two-Dimensional Molybdenum Disulfide Via Chemical Vapor Deposition

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Wright State University CORE Scholar Browse all Theses and Dissertations Theses and Dissertations 2019 Growth of Two-Dimensional Molybdenum Disulfide via Chemical Vapor Deposition Zachary Durnell Ganger Wright State University Follow this and additional works at: https://corescholar.libraries.wright.edu/etd_all Part of the Engineering Science and Materials Commons Repository Citation Ganger, Zachary Durnell, "Growth of Two-Dimensional Molybdenum Disulfide via Chemical aporV Deposition" (2019). Browse all Theses and Dissertations. 2174. https://corescholar.libraries.wright.edu/etd_all/2174 This Thesis is brought to you for free and open access by the Theses and Dissertations at CORE Scholar. It has been accepted for inclusion in Browse all Theses and Dissertations by an authorized administrator of CORE Scholar. For more information, please contact [email protected]. GROWTH OF TWO-DIMENSIONAL MOLYBDENUM DISULFIDE VIA CHEMICAL VAPOR DEPOSITION A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Materials Science and Engineering By ZACHARY DURNELL GANGER B.S.M.S.E. Wright State University, 2015 2019 Wright State University WRIGHT STATE UNIVERSITY GRADUATE SCHOOL March 28th, 2019 I HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER MY SUPERVISION BY Zachary Durnell Ganger ENTITLED Growth of Two Dimensional Molybdenum Disulfide via Chemical Vapor Deposition BE ACCEPTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Master of Science in Materials Science and Engineering. Committee on Final Examination ______________________________ Hong Huang, Ph.D. ________________________________ Thesis Director Hong Huang, Ph.D. Joseph C. Slater, Ph.D., P.E. ________________________________ Chair, Department of Mechanical and Materials Engineering Yan Zhuang, Ph.D. _______________________________ Shin Mou, Ph.D. _______________________________ Barry Milligan, Ph.D. Interim Dean of the Graduate School ABSTRACT Ganger, Zachary Durnell. M.S.M.S.E., Department of Mechanical and Materials Engineering, Wright State University, 2019. Growth of Two-Dimensional Molybdenum Disulfide via Chemical Vapor Deposition. Graphene has successfully been a 2D material applied in various fields, but it is not the most appropriate candidate for many electronic devices unless its bandgap structure is tuned through functionalization. Among all other 2D material families, transition metal dichalcogenides (TMDs), represented by molybdenum disulfide (MoS2), are promising and emerging in power electronics due to their large direct bandgap and other electronic properties. 2D MoS2 has been fabricated through different approaches such as mechanical exfoliation, chemical etching, and chemical vapor deposition (CVD). The current major challenge in fabricating 2D MoS2 films is to produce a high-quality large- area monolayer film at a controlled condition. This thesis study is to grow 2D MoS2 films by CVD method at various experimental settings and to characterize the size, thickness, and morphology of the films, towards finding an optimal processing condition. Experimental settings for the growth parameters include the precursor amounts and placements, growth time, growth temperature, carrier gas flow rate, substrates, and seeding promoters. The growth films are characterized with the help of optical microscopy, Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM). It is found that 1) MoS2 growth is sensitive to the carrier flow rate and temperature; and 2) 2D MoS2 grain size and areal coverage are correlated with grow time as well as the distance from the promoter PTAS (perylene-3,4,9,10-tetracarboxylic acid tetrapotassium salt) resource. Existence of monolayer MoS2, in the presence of PTAS promotor, is iii confirmed with Raman Spectroscopy and AFM. Multilayer MoS2 films with grains up to several hundreds of micrometers, confirmed with optical microscopy, SEM and Raman, are successfully grown on clean Si/SiO2 substrate in the presence of PTAS promotor vapor in the vicinity. Growth of monolayer/multilayer MoS2 on sapphire and graphene was also demonstrated. iv TABLE OF CONTENTS 1 INTRODUCTION AND BACKGROUND ............................................................................ 1 1.1 Motivation ........................................................................................................................ 1 1.2 Different Kinds of 2D Semiconducting Materials ............................................................... 3 1.2.1 First Generation 2D Materials - Graphene ................................................................................... 3 1.2.2 Second Generation 2D Materials ................................................................................................. 5 1.2.3 Third Generation 2D Materials .................................................................................................... 9 1.3 2D TMDs and Their Emerging Applications ...................................................................... 16 1.3.1 Overview of 2D TMDs……………………………………………………………………………………………………………16 1.3.2 Structure and Properties of 2D MoS2 ......................................................................................... 17 1.3.3 Fabrication of 2D MoS2 ............................................................................................................. 20 1.4 Research Objectives and Outline of this Thesis................................................................ 24 2 CURRENT RESEARCH ON CHEMICAL VAPOR DEPOSITION OF 2D MOLYBDENUM DISULFIDE .......................................................................................................................... 26 3 EXPERIMENTAL ASPECTS OF THIS STUDY ................................................................... 44 3.1 CVD Growth .................................................................................................................... 44 3.1.1 The CVD Setup………………………………………………………………………………...44 3.1.2 Growth Procedures……………………………………………………………………………..44 3.2 Growth Variables……………………….…………………………………………………..46 3.2.1 Position of Precursors………………..……..…………………………………………..………46 3.2.2 Growth Time…………………………..….….………………………………………………...47 3.2.3 Carrier Gas Flow Rate………………………………………………………………………….47 v 3.2.4 Quench Temperature………………………...………………………………………………...47 3.2.5 Substrate…………………...…………………………………………………………………..47 3.2.6 Substrate Surface Treatments…...……………………………………………………………..48 3.2.7 PTAS Promotors…………………...………………….……………………………………….49 3.3 Characterizations ............................................................................................................ 50 3.3.1 Optical Imaging and ImageJ Quantification Analysis ................................................................ 50 3.3.2 Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy ........................... 51 3.3.3 Atomic Force Microscopy .......................................................................................................... 52 3.3.4 Raman Spectroscopy .................................................................................................................. 53 4 RESULTS AND DISCUSSION ......................................................................................... 58 4.1 Preliminary Optimization ................................................................................................ 58 4.1.1 Processing Settings ..................................................................................................................... 58 4.1.2 Sulfur Position…………………………………………………………………………………60 4.1.3 MoO3 Position …………………………………………………………………………………61 4.1.4 Substrate………………………………………………………………………………………..62 4.2 Surface Treatments on Sapphire Substrate ..................................................................... 62 4.3 With PTAS Applied via Thermal Drying ............................................................................ 67 4.3.1 Drying Temperature ................................................................................................................... 67 4.3.2 Surface Treatment ...................................................................................................................... 68 4.4 With PTAS Applied via Spraying ...................................................................................... 69 4.4.1 Graphene Substrate with PTAS…...………………………………………………………………………………………71 4.5 PTAS Seeding Promoter on Separate Upstream Substrate ............................................... 73 4.5.1 Varying Amounts of PTAS.………………...………………………………………………...74 4.5.2 Varying Carrier Gas Flow Rate……………………………………………………………….80 vi 4.5.3 Varying Growth Time…………………………………………………………………………81 4.6 Quantitative Analysis……………………………………………………………………...84 5 CONCLUSION ............................................................................................................. 87 6 BIBLIOGRAPHY ........................................................................................................... 89 vii LIST OF FIGURES Figure 1: Graphene flake and atomic sketch [3] ............................................................................................................ 4 Figure 2: (a) α-, β-, and γ- graphyne, (b) graphdiyne, and (c) f extended graph-n-yne by acetylenic carbon chain length [8] ......................................................................................................................................................................
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